Conventionally, internal combustion engines such as automobile engines include an ignition device with an ignition plug that makes an ignition discharge to ignite a mixed gas of fuel and air. In recent years, internal combustion engines have been improved in fuel efficiency by lean combustion, and there has been a demand for enhancing ignition performance in lean combustion. For example, PTL 1 discloses an ignition plug in which a needle-like chip is formed on a ground electrode to improve ignition performance. In the ignition plug, a base material for the chip is formed from an inexpensive metal and end and side surfaces of the chip are partially covered with a precious metal to suppress the needle-like chip from wearing caused by a spark discharge and reduce the cost of the needle-like chip.